1. Field of the Invention
The present invention relates generally to optical scanning systems, and more particularly, to an automatic bar code symbol reading system in which an automatic optical scanner can be interchangeably utilized as either a portable optical scanner in an automatic xe2x80x9chands-onxe2x80x9d mode of operation, or as a stationary optical projection scanner in an automatic xe2x80x9chands-freexe2x80x9d mode of operation.
2. Brief Description of the Prior Art
Bar code symbols are widely utilized in many commercial environments such as, for example, point-of-sale (POS) stations in retail stores and supermarkets, inventory and document tracking, and diverse data control applications. To meet the growing demands of this recent technological innovation, bar code symbol readers of various types have been developed for scanning and decoding bar code symbol patterns and producing symbol character data for use as input in automated data processing systems.
In general, prior art hand-held bar code symbol readers using laser scanning mechanisms can be classified into two major categories.
The first category of hand-held laser-based bar code symbol readers includes manually-actuated, trigger-operated systems having lightweight laser scanners which can be supported in the hand of the user. The user positions the laser scanner at a specified distance from the object bearing the bar code symbol, manually activates the scanner to initiate reading and then moves the scanner over other objects bearing bar code symbols to be read. Prior art bar code symbol readers illustrative of this first category are disclosed in U.S. Pat. No. 4,387,297 to Swartz; U.S. Pat. No. 4,575,625 to Knowles; U.S. Pat. No. 4,845,349 to Cherry; U.S. Pat. No. 4,825,057 to Swartz, et al.; U.S. Pat. No. 4,903,848 to Knowles; U.S. Pat. No. 5,107,100 to Shepard, et al.; U.S. Pat. No. 5,080,456 to Katz, et al.; and U.S. Pat. No. 5,047,617 to Shepard, et al.
The second category of hand-held laser-based bar code symbol readers includes automatically actuated systems having lightweight triggerless laser scanners which can be supported in the hand of the user. The user positions the laser scanner at a specified distance from the object bearing the bar code, the presence of the object is automatically detected, the presence of the bar code symbol on the object is detected, and thereafter the detected bar code symbol automatically read. Prior art illustrative of this second category of laser-based bar code symbol reading systems are disclosed in U.S. Pat. No. 4,639,606 to Boles, et al., and U.S. Pat. No. 4,933,538 to Heiman, et al.
While prior art hand-held and stationary laser scanners have played an important role in the development of the bar code symbol industry, these devices have suffered from a number of shortcomings and drawbacks. For example, hand-held laser scanners, although portable and lightweight, are not always convenient to use in assembly-line applications where the user processes bar coded objects over an extended period of time, or where the user requires the use of both hands in order to manipulate the objects. In some applications, hand-held laser scanners are difficult to manipulate while simultaneously moving objects or performing other tasks at a point-of-sale terminal. Stationary laser scanners, on the other hand, provide a desired degree of flexibility in many applications by allowing the user to manipulate bar coded objects with both hands. However, by their very nature, stationary laser scanners render scanning large, heavy objects a difficult task, as such objects must be manually moved into or through the laser scan field.
Attempting to eliminate the problems associated with the use of hand-held and stationary laser scanners, U.S. Pat. No. 4,766,297 to McMillan discloses a bar code symbol scanning system which combines the advantages of hand-held and stationary fixed laser scanners into a single scanning system which can be used in either a hands-on or hands-free mode of operation. The bar code symbol scanning system in U.S. Pat. No. 4,766,297 includes a portable hand-held laser scanning device for generating electrical signals descriptive of a scanned bar code symbol. In the xe2x80x9chands-onxe2x80x9d mode of operation, a trigger on the hand-held laser scanning device is manually actuated each time a bar code symbol on an object is to be read. The system further includes a fixture having a head portion for receiving and supporting the hand-held laser scanning device, and a base portion above which the head portion is supported at a predetermined distance. In the hands-free mode of operation, the laser scanning device is supported by the fixture head portion above the fixture base portion in order to allow objects bearing bar code symbols to pass between the head and base portions of the fixture. In order to detect the presence of an object between the head and base portions of the fixture, the fixture also includes an object sensor operably connected to the hand-held laser scanning device. When the object sensor senses an object between the head portion and the base portion, the object sensor automatically initiates the hand-held laser scanning device supported in the fixture to read the bar code symbol on the detected object.
While the bar code symbol scanning system of U.S. Pat. No. 4,776,297 permits reading of printed bar code information using either a portable xe2x80x9chands-onxe2x80x9d or stationary xe2x80x9chands-freexe2x80x9d mode of operation, this system suffers from several significant shortcomings and drawbacks as well. In particular, in the hands-on mode of operation, scanning bar code symbols requires manually actuating a trigger each time a bar code symbol is to be read. In the hands-free mode of operation, scanning bar code symbols requires passing the object bearing the bar code between the head and base portions of the fixture. However, in many instances where both hands are required to manipulate a bar coded object, the object is too large to be passed between the head and base portions of the fixture and thus scanning of the bar code symbol is not possible.
In an attempt to address such problems, several hand-held projection laser scanners have been developed for omni-directional code symbol scanning. Examples of such systems include the NCR 7890 presentation scanner from the NCR Corporation and the LS9100 omni-directional laser scanner from Symbol Technologies, Inc. While each of these systems produces an omni-directional laser scan pattern from a hand-supportable housing and have hands-free and hands-on modes of operation, each of these scanning devices suffer from a number of shortcomings and drawbacks. In particular, the spatial extent of the laser scan pattern produced from each of these scanners frequently results in the inadvertent scanning of code symbols on products placed near the scanner during its hands-free mode of operation. In the hands-on mode of operation, it is virtually impossible to use the scanners to read bar code symbol menus provided in diverse application environments. Moreover, in each of these scanner designs, the scanner is tethered to its base unit by a power/signal cord. In the hands-on operational mode, the user is required to handle the scanner housing in an awkward manner, resulting in strain and fatigue and thus a decrease in productivity. In addition, the control structure provided in each of these hand-held projection scanners operates the scanner components in a manner which involves inefficient consumption of electrical power, and prevents diverse modes of automatic code symbol reading which would be desired in portable scanning environments.
Thus, there is a great need in the bar code symbol reading art for a bar code symbol reading system which overcomes the above described shortcomings and drawbacks of prior art devices and techniques, while providing greater versatility in its use.
Accordingly, it is a primary object of the present invention to provide an automatic bar code symbol reading system having an automatic optical scanning device which can be used at a point-of-sale (POS) station as either a portable hand-supported scanner when operated in its automatic hands-on mode of operation, or as a stationary projection scanner when operated in its automatic hands-free mode of operation.
It is another object of the present invention to provide such an automatic bar code symbol reading system, wherein a collimated scanning pattern is projected from the hand-supportable device about a projection axis, and intersects within a narrowly confined scanning volume so that bar code symbols disposed within the scanning volume can be read omnidirectionally, while inadvertent scanning of bar code symbols outside of the scanning volume is prevented.
It is another object of the present invention to provide such an automatic bar code symbol reading system, wherein the projection axis about which the narrowly confined scanning volume extends is substantially coplanar with the longitudinal axes of the head and handle portions of the hand-supportable housing.
It is another object of the present invention to provide such an automatic bar code symbol reading system, wherein the center-of-mass of the device is located within the hand-supportable portion to provide easy handling consistent with ergonomic design principles.
It is another object of the present invention to provide such an automatic bar code symbol reading system, in which one or more bar code symbols on an object can be automatically read in a consecutive manner.
A further object is to provide such an automatic bar code symbol reading device, in which the automatic hand-supportable bar code (symbol) reading device has an infrared light object detection field which spatially encompasses at least a portion of its visible laser light scan field along the operative scanning range of the device, thereby improving the laser beam pointing efficiency of the during the automatic bar code reading process of the present invention.
Another object of the present invention is to provide such an automatic bar code reading system in which a support frame is provided for supporting the housing of the device in a selected mounting position, and permitting gripping of the handle portion of the hand-supportable housing prior to removing it from the support frame.
It is another object of the present invention to provide an automatic bar code reading device which has both long and short-range modes of bar code symbol reading automatically selectable by placing the device within its support stand and removing it therefrom. With this particular embodiment of the present invention, the automatic bar code symbol reading system can be used in various bar code symbol reading applications, such as, for example, charge coupled device (CCD) scanner emulation and bar code xe2x80x9cmenuxe2x80x9d reading in the hands-on short-range mode of operation, and counter-top projection scanning in the hands-free long-range mode of operation.
An even further object of the present invention is to provide an automatic bar code reading device which prevents multiple reading of the same bar code symbol due to dwelling of the laser scanning beam upon a bar code symbol for an extended period of time.
A further object of the present invention is to provide a point-of-sale station incorporating the automatic bar code symbol reading system of the present invention.
It is a further object of the present invention to provide an automatic bar code reading device having a control system which has a finite number of states through which the device may pass during its automatic operation, in response to diverse conditions automatically detected within the object detection and scan fields of the device.
Another object of the present invention to provide a portable, automatic bar code symbol reading device, wherein the laser beam scanning motor is operated at a lower angular velocity during its object detection state of operation in order to conserve power consumption and facilitate rapid steady-state response when the device is induced to its bar code symbol detection and bar code symbol reading states of operation.
Another object of the present invention to provide a portable, automatic bar code symbol reading device, wherein the laser beam scanning motor is not energized during its object detection state of operation in order to conserve power consumption, and is momentarily overdriven to facilitate rapid steady-state response when the device undergoes a transition from the object detection state to the bar code symbol detection state of operation.
Another object of the present invention to provide a novel mechanism for mounting a laser scanning platform within the head portion of an automatic hand-supportable projection laser scanning device.
Another object of the present invention to provide a novel laser scanning platform for use within an automatic portable projection laser scanning device.
Another object of the present invention to provide a bar code symbol reading system having at least one bar code symbol reading device which, after each successful reading of a code symbol, automatically synthesizes and then transmits a data packet to a base unit positioned within the data transmission range of the bar code symbol reading device, and upon the successful receipt of the transmitted data packet and recovery of symbol character data therefrom, the base unit transmits an acoustical acknowledgement signal that is perceptible to the user of the bar code symbol reading device situated within the data transmission range.
A further object of the present invention is to provide such a system with one or more automatic (i.e., triggerless) hand-supportable laser-based bar code symbol reading devices, each of which is capable of automatically transmitting data packets to its base unit after each successful reading of a bar code symbol.
A further object of the present invention is to provide such a bar code symbol reading system in which the bar code symbol reading device can be used as either a portable hand-supported laser scanner in an automatic hands-on mode of operation, or as a stationary laser projection scanner in an automatic hands-free mode of operation.
A further object of the present invention is to provide such a bar code symbol system in which the base unit contains a battery recharging device that automatically recharges batteries contained in the device when the device is supported within the base unit.
It is another object of the present invention to provide such an automatic bar code symbol reading system with a mode of operation that permits the user to automatically read one or more bar code symbols on an object in a consecutive manner.
A further object of the present invention is to provide such an automatic bar code symbol reading system, in which a plurality of automatic bar code symbol reading devices are used in conjunction with a plurality of base units, each of which is mated to a particular bar code symbol reading device.
A further object of the present invention is to provide such an automatic bar code symbol reading system, in which radio frequency (RF) carrier signals of the same frequency are used by each bar code symbol reading device to transmit data packets to respective base units.
A further object of the present invention is to provide such an automatic bar code symbol reading system, in which a novel data packet transmission and reception scheme is used to minimize the occurrence of data packet interference at each base unit during data packet reception.
A further object of the present invention is to provide such an automatic bar code symbol reading system, in which the novel data packet transmission and reception scheme enables each base unit to distinguish data packets associated with consecutively different bar code symbols read by a particular bar code symbol reading device, without the transmission of electromagnetically-modulated data packet acknowledgment signals after receiving each data packet at the base unit.
A further object is to provide such an automatic bar code symbol reading device, in which the automatic bar code reading device has an infrared (IR) based object detection field which spatially encompasses at least a portion of its visible laser light scan field along the operative scanning range of the device, thereby improving the laser beam pointing efficiency of the device during the automatic bar code reading process of the present invention.
Another object of the present invention is to provide such an automatic bar code symbol reading system, in which the base unit has a support frame that supports the housing of the device in a selected mounting position, wherein the device is also supportable in the hand of a user, and wherein the support frame permits hand gripping of the handle portion of the hand-supportable housing prior to removing it from the support frame.
An even further object of the present invention is to provide an automatic bar code reading device which prevents multiple reading of the same bar code symbol due to dwelling of the laser scanning beam upon a bar code symbol for an extended period of time.
It is a further object of the present invention to provide an automatic bar code reading device having a control system which has a finite number of states through which the device may pass during its automatic operation, in response to diverse conditions automatically detected within the object detection and scan fields of the device.
It is yet a further object of the present invention to provide a portable, fully automatic bar code symbol reading system which is compact, simple to use and versatile.
Yet a further object of the present invention is to provide a novel method of reading bar code symbols using an automatic laser scanning device.
A further object of the present invention is to provide a point-of-sale station incorporating the automatic bar code symbol reading system of the present invention.
These and further objects of the present invention may be realized in any of various forms, many of which are described below in conjunction with the Detailed Description of the Preferred Embodiments and set forth in the appended Claims.